If a director has an opening in his schedule for a certain time period to direct a film and that film gets delayed month after month after month and he has no idea how long the delays will late, he CAN'T just tell the other scheduled movies that he will show up for an unknown period of time until he has to leave in the middle of shooting THAT film for 3 or 4 years to get back to the first film. What about the actors and others involved in the film that he will start and walk away from? Universal doesn't care about MGMs problems. They are in business to make money. If GDT tries to tell them that he will film part of their films that he has committed to film but that he will stop in the middle for years to do the Hobbit movies he will be legal toast.